Back in April, President Trump announced he would deploy National Guardsmen to California, Arizona, New Mexico and Texas to help secure and protect the U.S.-Mexico border until the wall can be built, and Trump called on the governors of the southwest states to support the efforts.

Citing the necessity to combat illegal crossings and drug trafficking, three out of four governors wholeheartedly supported the President’s decision. However, California Gov. Jerry Brown brought about the condition that the troops could not officially enforce immigration laws or help build the new border wall.

Chief Patrol Agent Gloria Chavez outlined the duties of the troops in a press conference on Monday. The troops will provide logistical and administrative support, operating detection systems, providing mobile communications and clearing vegetation from roads, among other tasks.

El Centro sector Border Patrol Chief Gloria Chavez welcomed 53 California National Guard members to her sector where they will support Border Patrol operations on the border. pic.twitter.com/MSxsnXvpTG

She anticipates 73 Guardsmen will support Border Patrol until at least Sept. 30, the end of the federal fiscal year.

Chavez called the National Guard’s help “critical” and confirmed that there has been “increased activity with regards to alien smuggling events” in the El Centro Sector, where the troops will be stationed.

“Their job is going to be behind the scenes, providing us with the critical support that today Border Patrol agents do,” Chavez said. “Where I need my Border Patrol agents is on the front line, doing the patrols and doing the interdiction of anything that crosses the border.”

According to Assistant Chief Patrol Agent David Kim, the sector is short about 200 agents, with the Guardsmen being tasked to fill that gap. However, law enforcement will not be part of the National Guard’s agenda.

Border Patrol officials have told the Guardsmen that if they encounter any illegal activity along the border, they should report it to the Border Patrol just as any citizen would.

“It will always be a Border Patrol agent making an arrest,” he said. “There’s no direct contact with the National Guard and anybody that may be committing a crime.”

The El Centro Sector has seen a steep decline in staffing since 2009, going from about 1,187 agents to just 870 in 2017, according to data from the U.S. Department of Homeland Security.